The following description is used to describe the background and products, materials and production methods that may comprise specific parts of preferred embodiments in the disclosure of this disclosure.
a) Laminate Floors
The majority of all laminate floors have a wood design. Such laminated floors have a core of 6-12 mm fibreboard, a 0.2 mm thick upper decorative surface layer of laminate and a 0.1-0.2 mm thick lower balancing layer. The decorative and wear properties are generally obtained with two separate layers of melamine formaldehyde impregnated paper, one above the other. The decorative layer is a printed paper and the wear layer is a transparent overlay paper, which comprises small aluminum oxide particles. The décor may be made with digital printing provided that a high quality pigment dispersion with small pigments is used.
b) Powder Based Floors
Recently new “paper free” floor types have been developed with solid surfaces comprising a substantially homogenous powder mix of fibres, binders and wear resistant particles hereafter referred to as WFF (Wood Fibre Floor).
The powder mix may comprise aluminum oxide particles, melamine formaldehyde resins and wood fibres. In most applications decorative particles such as, for example, colour pigments are included in the mix. In general, all these materials are applied in dry form as a mixed powder on a HDF core and cured under similar heat and pressure as used in laminate floors. Digital powder printing has been developed and it is possible to create very advanced wood, stone and tile designs by injecting water base ink into the powder prior to pressing. Such digital printing with water-based ink comprising pigment requires a high quality ink comprising very small pigments since rather small drops must be applied into the powder of in order to avoid bleeding during pressing when the melamine formaldehyde resin of the WFF floor surface floats.
c) LVT Floors
Luxury Vinyl Tiles, generally referred to as LVT floorings, are constructed as a layered product made of thermoplastic polyvinyl chloride (PVC) mixed with plasticizers. The name LVT is somewhat misleading since a major part of LVT floors have a plank shape with a wood pattern.
Thermal molding based on calendar rolling or extrusion is used to form the PVC layers. The core is made primarily of several layers that comprise PVC mixed with chalk and/or limestone fillers. A 0.1 mm high quality printed decorative PVC foil is applied on the upper side of the core. A transparent wear layer of vinyl with a thickness of 0.1-0.6 mm is generally applied on the decorative foil. The base layer, the decorative foil and the transparent layer are fused or laminated together with heat and pressure in continuous or discontinuous press operations. A transparent UV curing polyurethane (PU) lacquer is generally applied as a protective layer on the transparent PVC foil.
The decorative effects are obtained with a decorative foil that is printed separately and fused on the core layers. The foil comprises a single colour that generally is white and covers the dark colour of the core. The foil provides a base colour for the rotogravure printing process where special solvent-based inks are used to create wood, tile and stone designs.
d) WPC Floors
Wood Plastic Composite floors, generally referred to as WPC floors, are similar to LVT floors. The core comprises thermoplastic material mixed with wood fibre fillers and is generally stronger and much more rigid than the mineral-based LVT core. A printed image is protected by a transparent foil or a UV-curable lacquer in the same way as in LVT floors.
Thermoplastic material such as polyvinyl chloride (PVC), polypropylene (PP) or polyethylene (PE) may be combined with a mix of wood fibres and mineral particles and this may provide a wide variety of floor panels with different densities and flexibilities.
Some flooring producers have started to use digital printing technology to increase production flexibility and high quality prints of wood, tile and stone designs have been produced with expensive high quality inks comprising very small pigments. However, digital printing is only on an experimental stage and only small volumes are produced. The main reasons are that essentially the same printing technology and inks are used as in conventional desk top printing and the digital printing is not cost competitive compared to conventional printing technology based on large scale rotogravure printing.